Study Guide DNA Unit Flashcards
Chromosome
a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
Protein
made up of one or more long, folded chains of amino acids (each called a polypeptide), whose sequences are determined by the DNA sequence of the protein-encoding gene.
Amino Acid
the fundamental molecule that serves as the building block for proteins
DNA
Stands for deoxyribonucleic acid and contains genetic information, found in chromosomes located in nucleus of cells, composed of nucleotides (a single unit), contains sugar molecule (deoxyribose), phosphate group, nitrogen containing base (A,T,G,C). Double helix- two coiled DNA strands
Mitochondrial DNA
mtDNA. Found in the cytoplasm, is inherited only from mother. Each cell contains hundreds to thousands of mitochondria, can be found in skeletal remains. Analysis of mtDNA is more: rigorous, time consuming, costly than nucleic testing of DNA
Nucleotide
the basic building block of nucleic acids (RNA and DNA). A nucleotide consists of a sugar molecule (either ribose in RNA or deoxyribose in DNA) attached to a phosphate group and a nitrogen-containing base. The bases used in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T)
Complementary base pairing
adenine will always pair with its complement thymine and cytosine will always pair with its complement guanine
Semi conservative replication
Each DNA molecule resulting from replication has one original strand and one new strand
Mutation
Any change in the DNA sequence of a cell AKA an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Mutations may be caused by mistakes during cell division, or they may be caused by exposure to DNA-damaging agents in the environment. Mutations can be harmful, beneficial, or have no effect
VNTRs
Variable Numbers of Tandem Repeats- a type of repeating DNA sequence, the number of repeats varies from person to person, 9 to 80 bases in length
polymerase chain reaction (PCR) can be used to amplify the DNA that contains the VNTRs
Short Tandem Repeat
STR’s which are 2-5 bases in length. Shorter lengths make STR’s easier to use than VNTR’s
restriction enzymes are unnecessary; PCR allows the
amplication of the strands with STR sequences
DNA profiling/fingerprinting
used with a high degree of accuracy, biological evidence is examined for the presence of inherited traits. Some forensics laboratory techniques were originally developed for other purposes
PCR
(Polymerase chain reaction) allows the amplification of the strands with STR sequences. a laboratory technique for rapidly producing (amplifying) millions to billions of copies of a specific segment of DNA, which can then be studied in greater detail
Gel Electrophoresis
Bands of DNA are separated by size using electric current, DNA is mixed special enzymes, enzymes cut apart the DNA in specific places forming different sized fragments, DNA is separated within an agarose gel, an electric current is passed through the gel separating the fragments by size
Hydrogen bonds
bonds between bases hold the two strands together, G-C has 3, A-T has 2, can be broken easily, two strands can separate to be copied
CODIS
an acronym for Combined DNA Index System, which is a computer software program that operates local, state, and national databases of DNA profiles from convicted offenders, unsolved crime scene evidence, and missing persons
Denaturation
(Healing) - heat briefly to separate DNA strands. Due to abrupt changes in environmental conditions like temperature, pH etc., the DNA double helix unwinds and the hydrogen bonds between the base pairs are broken. favorable to DNA hybridization
Annealing
(Cooling)- cool to allow primers to bond with ends of DNA.
Extension
DNA polymerase adds nucleotides to the end of each primer
Primer
a short nucleic acid sequence that provides a starting point for DNA synthesis
DNA polymerase
enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA
Reasons to use DNA fingerprinting
identifying potential suspects, exonerating individuals (finding them not guilty/set free), identifying crime scenes and victims (burned bodies, decomposed bodies, etc), establishing paternity and proving family relations, matching organ donors, identifications of john doe or jane doe, studying evolution and ancestry (through nuclear and mitochondrial DNAs), studying inherited disorders
Steps of DNA replication
DNA molecule separates into two strands.
Then produces two complementary strands.
Each strand of the double helix of DNA serves as a template, or model, for the new strand
Steps of DNA fingerprinting
Extraction, Amplification, Gel Electrophoresis and Probes
Steps of DNA extraction
- Cells are isolated from biological evidence such as blood, saliva, urine, semen and hair
- The cells are broken to release the DNA from proteins and other cell components
- The DNA can be extracted from the cell nucleus
Steps of PCR amplification
- Denaturation (heating)
- Annealing (cooling)
- Extension
Steps of gel electrophoresis
Bands of DNA are separated by size using electric current
DNA is mixed with special enzymes
Enzymes cut apart the DNA in specific places forming different sized fragments
DNA is separated within an agarose gel
An electric current is passed through the gel separating the fragments by size
NOTE: Shorter=faster, Longer=slower
How do restriction enzymes work?
What are restriction enzymes and how do they work?
Restriction enzymes are DNA-cutting enzymes. Each enzyme recognizes one or a few target sequences and cuts DNA at or near those sequences
What did James Watson, Francis Crick and Rosalind Franklin do?
they discovered the configuration of the DNA molecule
What did Ray White do?
he described the first polymorphic RFLP marker
What did Alec Jeffreys do?
he isolated DNA markers and called them DNA fingerprints
What did Kary Mullis do?
he developed PCR testing
